Department of Biosystems, Faculty of Bioscience Engineering, University of Leuven (KU Leuven), Kasteelpark Arenberg 30, B-3001 Heverlee, Belgium.
Res Microbiol. 2013 May;164(4):310-8. doi: 10.1016/j.resmic.2013.01.003. Epub 2013 Jan 30.
Extraintestinal pathogenic Escherichia coli (ExPEC) contain tktA and tktB which code for transketolases involved in the pentose phosphate pathway. Recent studies demonstrated that a third gene coding for transketolase 1 (tkt1) was located in a pathogenicity island of avian and human ExPEC belonging to phylogenetic group B2. In the present study, in silico analysis of tkt1 revealed 68% and 69% identity with tktA and tktB, respectively, of ExPEC and 68% identity with tktA and tktB of E. coli MG1655. The translated tkt1 shared 69% and 68% identity with TktA and TktB proteins, respectively, of ExPEC and E. coli MG1655. Phylogenetically, it is shown that the three genes (tktA, tktB and tkt1) cluster in three different clades. Further analysis suggests that tkt1 has been acquired though horizontal gene transfer from plant-associated bacteria within the family Enterobacteriaceae. Virulence studies were performed in order to evaluate whether tkt1 played a role in avian pathogenic E. coli CH2 virulence in chickens. The evaluation revealed that mutant virulence was slightly lower based on LD50 when compared to the wild type during infection of chickens, but there were no significant differences when the two strains were compared based on the number of deaths and lesion scores.
肠外致病性大肠杆菌（ExPEC）含有 tktA 和 tktB，它们编码参与戊糖磷酸途径的转酮醇酶。最近的研究表明，编码转酮醇酶 1（tkt1）的第三个基因位于属于 B2 群的禽源性和人源性 ExPEC 的一个致病性岛中。在本研究中，tkt1 的计算机分析显示，其与 ExPEC 的 tktA 和 tktB 分别具有 68%和 69%的同一性，与大肠杆菌 MG1655 的 tktA 和 tktB 分别具有 68%的同一性。翻译的 tkt1 与 ExPEC 和大肠杆菌 MG1655 的 TktA 和 TktB 蛋白分别具有 69%和 68%的同一性。系统发育分析表明，这三个基因（tktA、tktB 和 tkt1）聚类在三个不同的分支中。进一步的分析表明，tkt1 是通过水平基因转移从肠杆菌科的植物相关细菌中获得的。进行了毒力研究，以评估 tkt1 是否在禽致病性大肠杆菌 CH2 对鸡的毒力中发挥作用。评估结果表明，与野生型相比，感染鸡时突变体的毒力略低，但基于死亡率和病变评分，两种菌株之间没有显著差异。
